Method and system for selective or isolated integrate cerebral perfusion and cooling

ABSTRACT

Patients having diminished circulation in the cerebral vasculature as a result of cardiac arrest or from other causes are treated by flowing an oxygenated medium through an arterial access site into the cerebral vasculature and collecting the medium through an access site in the venous site of the cerebral vasculature. In addition to oxygenation, the recirculating blood may also be cooled to hypothermically treat and preserve brain tissue. Isolation and cooling of cerebral vasculature in patients undergoing aortic and other procedures is achieved by internally occluding at least the right common carotid artery above the aortic arch. Blood or other oxygenated medium is perfused through the occluded common carotid artery(ies) and into the arterial cerebral vasculature. Usually, oxygen depleted blood or other medium leaving the cerebral vasculature is collected, oxygenated, and cooled in an extracorporeal circuit so that it may be returned to the patient.

[0001] This is a continuation of Barbut et al., U.S. application Ser.No. 09/904,016, filed Jul. 11, 2001, which is a continuation of Barbutet al., Ser. No. 09/256,965, filed Feb. 24, 1999, which is acontinuation-in-part of Barbut et al., U.S. Application Serial No.60/076,222, filed Feb. 25, 1998, entitled “Method and System forEmergency Cerebral Perfusion,” and a continuation-in-part of U.S.Application Serial No. 60/096,218, filed Aug. 12, 1998, entitled“Methods and Apparatus for Isolation of the Cerebral Vasculature.” Allof the above-identified applications are expressly incorporated hereinby reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to medical devices andmethods. More particularly, the present invention relates generally tomethods, systems, and kits for perfusing and optionally cooling thecerebral vasculature of a patient with oxygenated blood or other media.

[0003] Cerebral ischemia, i.e., reduction or cessation of blood flow tothe cerebral tissue, can be characterized as either focal or global.Focal cerebral ischemia refers to reduced perfusion to the cerebraltissue resulting from a partial or complete occlusion in theintracranial or extracranial cerebral arteries, e.g., stroke,subarachnoid hemorrhage spasms, iatrogenic vasospasm. Global cerebralischemia refers to reduced perfusion to the cerebral tissue resultingfrom systemic circulatory failure caused by, e.g., cardiac arrest,shock, circulatory arrest, and septicemia.

[0004] Cardiac arrest is a major contributor to global cerebralischemia. Cardiac arrest refers to cessation or significant reduction ofa patient's cardiac output and effective circulation to vital organs,most importantly the brain. Cardiac arrest can result from a number ofcauses, such as electrical dysfunction, mechanical failure, circulatoryshock, or an abnormality in ventilation. Within minutes of blood flowcessation, tissue becomes ischemic (oxygen deprived), particularly inthe heart and brain. Brain tissue is perhaps most immediately at risk,with severe, irreversible damage occurring minutes after the initialcardiac arrest. Patients in cardiac or circulatory arrest are usuallytreated by a combination of forced ventilation of the lungs and forcedcompression of the heart. Most commonly, cardiopulmonary resuscitation(CPR) is applied to the patient, with manual chest compression andmouth-to-mouth resuscitation. Advanced cardiac support (ACS) may also beprovided in the form of drugs, defibrillation, and other techniques.Less commonly, open chest massage of the heart may be performed,particularly in a hospital setting where skilled surgeons may bepresent. Open chest heart massage is probably the most effectivetechnique at resuscitating a patient and avoiding ischemic brain damage,but the technique is quite invasive and not available in most emergencysituations.

[0005] CPR and other techniques which are directed at mechanical heartcompression and lung ventilation do not usually provide adequate brainoxygenation. In addition, vasoconstrictors, e.g., epinephrine,administered during CPR are often either ineffective or given in dosagestoo high to produce systemic blood pressure required for cerebralperfusion. In the best cases, conventional cardiac resuscitationtechniques will provide no more than 1 l/min of total blood circulation(with only about 200 ml/min passing through the cerebral vasculature)and no more than 5 to 15 mmHg of blood pressure. Normal circulation andblood pressure are 5 l/min and 80 to 100 mmHg, respectively, with about1 l/min passing through the cerebral vasculature. Such flows are usuallynot adequate at normothermia. Even when CPR techniques are appliedwithin the first several minutes of a cardiac arrest, the percentage ofpatients who survive without significant brain damage is very low.Significantly, most patients suffering from cardiac arrest die becauseof cerebral hypoperfusion.

[0006] Recognizing such problems, alternative techniques for treatingpatients in cardiac arrest have been proposed. Of particular interest tothe present invention, the emergency use of cardiopulmonary bypassmachines for supporting and cooling systemic circulation has beenproposed. Generally, access is provided with a pair of catheters, whereone of the catheters may be balloon-tipped to partition the circulationand permit the desired bypass. While such systems are theoreticallyeffective, they do not isolate the cerebral vasculature and do notnecessarily provide sufficient oxygenation of the brain. Moreover, theneed to deploy intravascular catheters is time consuming and must beperformed by a highly skilled and trained personnel.

[0007] Surgical procedures on the aorta are required for the treatmentof a number of conditions, such as aortic aneurysms, occlusionaldiseases, aortic dissection, and the like. Exemplary procedures includeconventional aortic aneurysm repair and grafting, endarterectomy for thetreatment of aortic atheroma, stenting for the treatment of aorticatheroma or dissection, and the like. Such procedures frequently requirethat the aorta be surgically opened to permit reconstruction or othersurgical modification. Surgically accessing and opening the aorta willusually further require that the patient's circulation be arrested,i.e., blood flow through the aorta cannot be accommodated while theaorta is being surgically accessed. Cessation of systemic circulationplaces a patient at great risk, particularly in the cerebral vasculaturewhere ischemia can rapidly lead to irreversible brain damage.

[0008] A number of techniques have been proposed to at least partiallyprotect a patient having arrested circulation during a variety of aorticprocedures. It will be appreciated that conventional cardiopulmonarybypass (CABG) techniques will generally not be useful when the aortadoes not remain in tact. Thus, various alternative protective protocolshave been proposed.

[0009] Retrograde aortic perfusion (RAP) can be used when a procedure isbeing performed on the aorta between the heart and the aortic arch. Theaorta is clamped beneath the aortic arch and retrograde aortic perfusionestablished, typically via femoral access. Advantageously, suchretrograde perfusion can continue throughout the procedure since theoperative site within the aorta is isolated by the clamp. RAP, however,is disadvantageous in a number of respects. In particular, retrogradeperfusion often results in significant cerebral embolization fromdislodgment of atheromatous material in the descending aorta and aorticarch. Such risk, as well as the limited region of the aorta that can beoperated on, makes PAP less than ideal. Moreover, RAP is not useful forprocedures distal or proximal to the isolated region of the aorta and isuseful only at the beginning of procedures performed within the isolatedaortic region.

[0010] Another approach for protecting the brain during aortic archprocedures is referred to as hypothermic circulatory arrest (HCA). HCArelies on inducing marked hypothermia in the entire body prior tostopping blood circulation altogether. Circulation remains stoppedduring the entire aortic procedure, thus placing the patient atsignificant risk of ischemia (despite the hypothermia). The patient isat further risk because the whole body has been cooled, thus increasingthe duration of the surgery to accommodate the time needed to return tonormal body temperature. HCA has also been associated with systemiccoagulopathy (impaired coagulation) in a significant number of patients.Coagulopathy can require blood and plasma transfusion, both of whichhave been associated with the risk of viral infection. Aortic surgeryperformed with HCA has a very high morbidity, typically about 20%.

[0011] In order to retain some cerebral circulation during the time theaortic arch is accessed, HCA may be combined with retrograde cerebralvenous perfusion (RCP). A catheter is placed in the superior vena cavaand oxygenated blood introduced. Flow is established in a retrogradedirection up the vena cava into the brachial and jugular veins.Unfortunately, very little of the oxygenated blood will reach thecerebral vessels for a number of reasons. For example, as much as 85% ofthe blood will enter the brachial veins and go to the arms with aslittle as 205 of the blood entering the brain. Moreover, the jugularvenous valves may inhibit the blood from reaching the cerebral vessels.Blood that does reach the cerebral veins immediately flows outwardlythrough the extensive collateral circulation without perfusing the braintissue. The amount of blood that returns to the aorta from the carotidarteries represents no more than about 5% of the total blood that isinitially introduced to the superior vena cava. Additionally, asobserved by the inventor herein, such retrograde perfusion results in abuild up of the cerebral pressure that further inhibits any bloodinflow. For these reasons, HCA, even when combined with RCP, falls farshort of providing adequate protection for the patient during proceduresperformed on the aorta.

[0012] Another procedure for perfusing the brain during aorticprocedures has recently been proposed. The procedure is referred to asselective antegrade cerebral perfusion (SCP) and relies on introducing acatheter through the aorta into a carotid artery in order to perfuse thecerebral vasculature. Introduction of the catheter can dislodgeatheromatous material which will often be present at the take-off fromthe aorta and which may thus cause cerebral embolization. Furthermore,in order to prevent air from entering the cerebral vessels, the carotidartery and all other cerebral arteries must be externally clamped orsnared, which can cause atheromatous embolization. While the procedurecan more effectively maintain cerebral perfusion than HCP, alone orcombined with RCP, the risk of both air and atheromatous embolizationmore than outweighs any associated benefits from enhanced perfusion.

[0013] It would therefore be desirable to provide improved methods andsystems for perfusing the cerebral vasculature of a patient sufferingfrom either focal or global cerebral ischemia with oxygenated blood orother media in patients. Such methods and systems should be suitable forrapid deployment, be capable of use outside of a hospital environment,and should be capable of being performed with less skilled personnelthan comparable catheter-based systems. Preferably, such systems may bedeployed via direct percutaneous cannulation of the patient vasculature.In addition, the method and systems of the present invention should besuitable for use with patients undergoing cardiac and vascularprocedures where it is desirable to perfuse and/or isolate the cerebralvasculature. At least some of these objectives will be met by theinvention of the present application.

[0014] For these reasons, it would be desirable to provide improvedmethods, systems, and kits for protecting the brain and cerebralvasculature during the performance of surgical procedures on the aorta.In particular, it would be desirable to provide for cerebral perfusionwhich is both antegrade and continuous throughout performance of theaortic procedure and which would enable profound cerebral hypothermiawithout systemic hypothermia. It would be further desirable to providefor improved isolation of the cerebral vasculature, still morepreferably with minimum and ideally no external clamping. It would bestill further desirable to minimize the risk of air and/or atheromatousembolization in the cerebral vasculature or elsewhere as a result of theaortic procedure. Such methods, systems, and kits should be compatiblewith reduced and/or localized hypothermia, particularly hypothermiadirected specifically at the cerebral vasculature. In addition, cerebralisolation, perfusion and cooling should be compatible with systems andmethods for perfusing non-cerebral portions of the patient'svasculature. At least some of these objectives will be met by theinvention described hereinafter.

DESCRIPTION OF THE BACKGROUND ART

[0015] Selective cerebral perfusion (SCP) procedures are described inKazui et al. (1992) Ann. Thorac. Surg. 53:109-114; Mohri et al. (1993)Ann. Thorac. Surg. 56:1493-1496; and Tanaka et al. (1995) Ann. Thorac.Surg. 59:651-657. Advanced cardiac life support techniques are discussedand compared in Tucker et al. (1995) Clin. Cardiol. 18:497-504.Emergency cardiopulmonary bypass using access needles introduced via acut-down procedure is described in Litzie, U.S. Pat. No. 4,540,399.Emergency cardiopulmonary bypass using catheter-based access isdescribed in Safar et al., U.S. Pat. No. 5,383,854; Safar et al., U.S.Pat. No. 5,308,320; Buckberg et al., U.S. Pat. No. 5,011,469; and Safar(1993) Ann. Emerg. Med. 22:58/324-83/349. A cardiopulmonary bypasssystem with cooling having a balloon tipped cannula for accessing theinferior vena cava and an anastomotically attached catheter foraccessing the femoral artery is described in Sausse, U.S. Pat. No.3,881,483. Cerebral infusion with cooled and/or preservative media isdescribed in Klatz et al., U.S. Pat. Nos. 5,149,321; 5,234,405;5,395,314; 5,584,804; and 5,653,685. Aortic perfusion with ballooncatheters is described in Paradis, U.S. Pat. No. 5,334,142; Manning,U.S. Pat. No. 5,437,633; and Manning et al. (1992) Ann. Emerg. Med.21:28-35. Coronary and/or cerebral retroperfusion is described in Pizonet al., U.S. Pat. No. 4,459,977; Jackson, U.S. Pat. No. 4,850,969;Jackson, U.S. Pat. No. 4,917,667; and Grady, U.S. Pat. No. 5,084,011.Other relevant patents include Barkalow et al., U.S. Pat. No. 4,198,963;Ward et al., U.S. Pat. No. 5,531,776; and Meyer, I I I, U.S. Pat. No.5,626,143.

SUMMARY OF THE INVENTION

[0016] According to the present invention, methods, systems, and kitsare provided for perfusing an oxygenated medium, usually autologousblood, through the cerebral vasculature of patients suffering fromglobal ischemia caused by, e.g., cardiac arrest, shock, circulatoryarrest, and septicemia; focal ischemia caused by stroke, subarachnoidhemorrhage spasms, iatrogenic vasospasm; or, cerebral edema, e.g., headtrauma. The method, systems, and kits are useful not only in providingselective isolated cerebral perfusion during all conditions of cerebralischemia, but also in reducing the dosage of vasoconstrictors requiredto achieve a desired perfusion pressure.

[0017] Optionally, in addition to improving cerebral perfusion, themethods of the present invention may combine or otherwise rely oncooling of the patient's head and cerebral vasculature in treatment ofboth global and focal cerebral ischemia to inhibit tissue damageresulting from lack or limitation of cerebral blood circulation.Usually, the oxygenated medium which is circulated as part of themethods of the present invention will be cooled in order to cool thebrain tissue and reduce the risk of ischemic damage. Further optionally,the patient's head may be cooled even prior to initiating perfusion ofexternally oxygenated, optionally cooled blood. In some instances, thecooled blood can be used to externally cool the patient's head duringthe treatment protocol, e.g., by passing the blood through a helmet orother structure which permits the blood to selectively cool the head.This selective isolated cooling of the head and/or cerebral vasculatureis desirable and preferred over systemic cooling, since coagulopathy,poor healing, cardiac arrhythmia and cardiac arrest can ensue as aresult of systemic cooling.

[0018] The methods of the present invention for improving cerebralperfusion comprise accessing at least one extracranial vein, such as theinternal jugular vein, the femoral vein, and/or the subclavian vein, andaccessing at least one artery which feeds the cerebral vasculaturethrough incisions on any extracranial artery, such as the common carotidartery, the internal carotid artery, the femoral artery, or thesubclavian artery. In providing both selective isolated perfusion andcooling of the cerebral tissue, the methods comprise assessing at leastone thing at location(s) which drain at least a portion of the cerebralvasculature, such as the internal jugular vein and/or external jugularvein, and assessing at least one artery which feeds the cerebralvasculature through incisions on any extracranial artery, such as thecommon carotid artery, the internal carotid artery, the femoral artery,or the subclavian artery. In emergency cases, access will usually beprovided by a percutaneous needle stick as described in more detailbelow. When performed in conjunction with aortic arch or other cardiacsurgery, in contrast, the access will usually be provided via surgicalexposure of the target vein(s) and artery(ies). An oxygenated medium isflowed from the arterial access location through the cerebralvasculature to the venous access location in order to perfuse thecerebral vasculature with the oxygenated medium. The vein(s) andartery(ies) are chosen to provide access to at least a major portion ofthe blood circulation through the cerebral vasculature. Preferably, thevein(s) and artery(ies) will also be directly accessible via apercutaneously inserted needle or other cannula for emergencyperformance of the procedures in the field. Suitable veins include theinternal and/or external jugular vein, the superior vena cava, and thelike. Suitable arteries include the common carotid arteries, theexternal and internal carotid artery, and the like. The particularaccess sites in each of the artery and vein will be selected basedprimarily on percutaneous accessibility. Preferred venous access siteslie within the internal jugular vein and preferred venous access siteslie within the common carotid artery.

[0019] After access is established, typically using percutaneouslyintroduced needles, cannulas, or other conduits, a flow of oxygenatedmedium is initiated at a rate sufficient to provide oxygen to the braintissue. The rate will depend on the amount of oxygen being carried bythe oxygenated medium, typically being in the range from 0.1 l/min to1.5 l/min, typically from 0.2 l/min to 1 l/min. For oxygenatedautologous blood, the rate will typically be in the range from 0.2 l/minto 1 l/min. In some instances, in order to inhibit possible reperfusioninjury, it will be desirable to initiate the flow rate of oxygenatedmedium at a relatively low rate and subsequently increase the flow rateto a final rate within the ranges set forth above. Usually, the finalflow will be maintained at a steady rate, but it will also be possibleto initiate a pulsatile or other non-steady flow rate.

[0020] In order to enhance the efficiency of oxygenated medium deliveredto the cerebral vasculature, it will usually be desirable to at leastpartly occlude the access blood vessel(s) near the access sites in orderto prevent flow away from the cerebral vasculature. That is, at thevenous access site(s), the vein will be occluded in order to inhibitflow caudal to the access location. At the arterial access site(s), theartery will be occluded to inhibit flow into the aorta. As described inmore detail in connection with the systems of the present invention,such occlusion will typically be provided by inflatable occludingballoons on the access needles, cannulas, or other conduits.

[0021] In the preferred methods of the present invention, the oxygenatedmedium will consist essentially of blood, usually patient autologousblood, and the blood will be recirculated from the venous accesslocation to the arterial access location using a pump. In addition tothe primary antegrade flow, some flow may occur in a retrogradedirection to the contralateral hemisphere and/or posterior territoriesas well. The blood will be extracorporeally oxygenated and optionallycooled, typically to a temperature in the range from 7° C. to 35° C.External pumping, oxygenation, and cooling can be provided by systems ofa type used for cardiopulmonary bypass procedures.

[0022] Alternatively, the oxygenated medium may comprise a syntheticoxygen carrier, such as a perfluorocarbon, or other synthetic bloodsubstitute material. In some instances, such synthetic oxygen carriersmay be combined with patient or non-autologous blood. The syntheticoxygen carriers may be preoxygenated and flowed through the cerebralvasculature only once. In such cases, a large reservoir of the syntheticoxygen carrier may be provided, passed through the cerebral vasculature,and collected as it passes out of the venous access site. Alternatively,the synthetic oxygen medium, optionally combined with blood, may beextracorporally recirculated and oxygenated as described above forautologous blood.

[0023] In all cases, the oxygenated medium may have other biologicallyactive agents combined therewith. For example, drugs and biologicalagents which inhibit deterioration of brain tissue in cases of limitedoxygen supply may be utilized. Such compositions include NMDAreceptor-inhibitors, calcium-channel blockers, anticoagulants, glutamateinhibitors, free-radical inhibitors, vasodilators, and the like.

[0024] The present invention still further provides improved methods forselective isolated cerebral perfusion in patients with global or focalischemia. Such improved methods comprise isolating at least a portion ofthe patient's cerebral vasculature from the remainder of patientcirculation, typically by partitioning using occlusion balloons asdescribed in more detail hereinafter. Patient blood is oxygenated andrecirculated through the isolated vasculature in order to inhibitischemia and resulting damage to brain tissue while steps are taken totreat the cardiac arrest.

[0025] In yet another aspect of the method of the present invention,improved antegrade cerebral perfusion with an oxygenated mediumcomprises introducing the oxygenated medium, typically autologous blood,to a carotid artery to establish antegrade flow into the cerebralvasculature. The oxygenated medium, after it has passed through thecerebral vasculature, is collected through a jugular vein. Such improvedmethods may be used with both once-through perfusion using a syntheticoxygen carrier and/or heterologous oxygenated blood. More usually, suchimproved methods will be used with extracorporeal recirculation andoxygenation of autologous blood.

[0026] Systems according to the present invention for recirculating andoxygenating blood in the cerebral vasculature of a patient comprise avenous cannula, an arterial cannula, a pump, and an oxygenator. Thevenous cannula typically has a lumen diameter in the range from 2 mm to4 mm and includes a distal occlusion balloon, wherein the cannula andballoon are sized to access and occlude a vein which drains the cerebralvasculature, typically a jugular vein. The arterial cannula typicallyhas a lumen diameter in the range from 2 mm to 4 mm and also has adistal occlusion balloon, and the cannula and balloon are sized toaccess and occlude an artery which feeds the cerebral vascular,typically the common carotid artery. The pump may be connected betweenthe venous cannula and the arterial cannula to circulate blood from thevenous cannula to the arterial cannula, typically at a flow rate in theranges set forth above. The oxygenator processes the externallycirculating blood to provide a desired degree of oxygenation, alsowithin the ranges set forth above.

[0027] The present invention still further provides kits including avenous cannula sized to access a vein which drains the cerebralvasculature and an arterial cannula sized to access an artery whichfeeds the cerebral vasculature. Such kits will further includeinstructions for use according to any of the methods set forth above.Additionally, the kits may comprise a package for holding all or aportion of the kit components, typically in a sterile condition. Typicalpackages include trays, pouches, boxes, tubes, and the like. Preferably,the cannulas will each have an occlusion balloon sized to occlude therespective blood vessel lumen into which they are placed. Other optionalkit components include oxygenated medium, drugs to be delivered via theflowing blood or other oxygenated medium, catheters for connecting thecannulas to an extracorporeal recirculation/oxygenation cooling system,cassettes for use with such extracorporeal recirculation systems,cooling elements, thermometers, pressure transducers, and the like.

[0028] In still other embodiments, methods, systems, and kits areprovided for isolating and perfusing the cerebral vasculature, usuallyto facilitate access to a patient's aorta, during performance of adiagnostic or interventional procedure on the aorta, more usually duringperformance of an open surgical interventional procedure on the aorta,such as repair of an aortic aneurysm, dissections, reconstruction of theaorta, endarterectomy, or the like. The heart will usually be arrestedduring open surgical procedures where the aorta is opened and procedureis performed within the lumen of the aorta. In some instances, however,the heart may remain beating while the procedure is performedintravascularly, i.e. through using catheters and other instrumentsintroduced from the peripheral vasculature and into the aorta. Themethods of the present invention will serve primarily to isolate thecerebral vasculature and prevent gaseous and atheromatous emboli fromentering the cerebral vasculature while the vasculature is perfused withan oxygenated medium.

[0029] Methods according to the present invention comprise internallyoccluding blood flow to the arterial cerebral vasculature at alocation(s) above the aortic arch. At a minimum, blood flow to the rightcerebral vasculature will be internally occluded. Preferably, blood flowto both the right and left cerebral vasculature is internally occluded.Such internal occlusion is usually accomplished using an expansibleoccluder or partial occluder with central lumen, such as an inflatableballoon positioned at the distal end of a catheter, cannula, or otheraccess device. The access device further provides for perfusion of anoxygenated medium into the occluded artery distal to the point ofocclusion, e.g., the device may have a lumen that delivers the medium ata suitable positive pressure.

[0030] Occlusion of blood flow from the aortic arch and perfusion ofoxygenated medium to the arterial cerebral vasculature may beaccomplished in a number of ways, e.g., by occluding the right commoncarotid artery or by occluding an upstream portion of thebrachiocephalic artery which-feeds the right carotid artery. In bothcases, the oxygenated medium can be perfused distally of the balloon orother occluding device so that it flows up through the right commoncarotid artery into the cerebral vasculature. When occluding thebrachiocephalic artery and perfusing the oxygenated medium upstream ofthe right common carotid artery, it may be desirable to at leastpartially inhibit blood flow through the right subclavian artery, e.g.using another occluding balloon or using an externally appliedtourniquet on the arm. Inhibiting the loss of oxygenated medium to thearm helps redirect the medium to the cerebral arterial vasculaturethrough both the right common carotid artery as well as the rightvertebral artery, assuming that the subclavian artery is occluded at apoint distal to the vertebral arterial branch. Other, more complexocclusion patterns could also be employed, although not necessarilybeing preferred.

[0031] Occlusion of blood flow from the aortic arch and perfusion ofoxygenated medium to the left arterial cerebral vasculature may beeffected within the left common carotid artery, the left subclavianartery, and/or the left vertebral artery. When blood or other oxygenatedmedium is introduced into the left subclavian artery, it may further bedesirable to inhibit blood flow into the arm, e.g., by internally orexternally occluding the left subclavian artery at a point that preventssuch blood flow.

[0032] In a presently preferred procedure, occluding balloons will bepositioned within the brachiocephalic artery, the left common carotidartery, and the left subclavian artery. Both the right subclavian arteryand the left subclavian artery will be blocked, preferably with externaltourniquets on the arms. Blood or other oxygenated medium will then beperfused into the arterial cerebral vasculature to points immediatelyupstream of each of the occluding balloons, preferably using lumens orother infusion components incorporated within the occluding devicesthemselves. Inhibition of blood flow down into the arms is beneficialsince it redirects the blood or other oxygenated medium back into thecerebral arterial vasculature. While this approach may be optimal inmany ways, the present invention can be carried out in other ways aswell. Most simply, internal occlusion of the right brachiocephalicartery and perfusion of oxygenated medium distal to the point ofocclusion may be sufficient in some cases by itself.

[0033] In many cases, it will be desirable to occlude the arteries at apoint as close to the aortic arch as possible. In particular, this istrue of the brachiocephalic artery, the left carotid artery, and theleft subclavian artery which branch directly from the aortic arch.Occlusion close to the aortic arch (i.e., immediately above the branchor within 3 cm thereof) is of benefit primarily because it enables thesurgeon to access the artery and initiate the occlusion with minimalaortic dissection toward the neck. In other cases, of course, it will bepossible to access any one of the brachiocephalic artery at a pointclose to the aortic arch and to intravascularly advance an occludingballoon or other devise to a desired point of occlusion. In someinstances, it may even be desirable to deliver and position devicescarrying multiple occluding balloons and/or lumens for deliveringoxygenated medium to the cerebral arterial vasculature.

[0034] Access to the occlusion site and the target artery may beobtained in a variety of ways. For example, the target artery may besurgically exposed when the chest and neck are opened as part of aprocedure being performed on the aortic arch. In such cases, smallincisions can be made directly into the wall of the target artery topermit introduction of the occluder. Alternatively, in procedures thatare performed away from the aortic arch and/or where it is not desiredto surgically open the patient above the target sites within thearteries, the target sites can be accessed by conventional cut-downprocedure or a needle-based procedure, such as the Seldinger technique.As yet another alternative, the arterial vasculature can be accessed ata point remote from the desired point of occlusion, e.g. in the femoralartery or in an artery of the arm, such as the axillary or brachialartery. The balloon or other occluding member on the catheter may thenbe intravascularly advanced from the access location to the desiredpoint of occlusion in a conventional manner, e.g. over a guidewire underfluoroscopic observation. An approach to a desired occlusion pointwithin the brachiocephalic artery and/or the right common carotid arteryfrom an artery in the arm may be preferred since no catheter would bepresent in the aortic arch itself.

[0035] The oxygenated medium will usually be blood, more usually beingautologous blood obtained from the patient being treated. In the mostusual cases, patient blood will be recirculated through a conventionalblood pump and oxygenator so that the patient may be continuouslysupplied with oxygen in the perfused cerebral vasculature. The blood orother oxygenated medium will also be cooled in order to induce selectivehypothermia within the cerebral vasculature. A preferred hypothermictemperature for the brain will be in the range from 7° C. to 35° C.,more preferably from 9° C. to 30° C. The actual temperature that ismaintained will depend both on the temperature and the flow rate of theoxygenated medium, with higher flow rates generally requiring lesscooling to achieve the target hypothermic temperature. Useful flow ratesfor the oxygenated medium will be in the range from 300 ml/minutes to1500 ml/minutes, typically from 400 ml/minute to 1000 ml/minute withouthypothermia, and from 80 ml/minute to 600 ml/minute, typically from 150ml/minute to 400 ml/minute with hypothermia induced in the patient.Generally, the patient requires progressively less oxygen with increasedhypothermia, allowing the flow rates of oxygenated cooled medium to bedecreased. A sufficient flow of the oxygenated medium should bemaintained, however, in order to maintain the desired level ofhypothermia. Suitable temperatures will be in the range from 8° C. to35° C., typically from 14° C. to 30° C. It will be appreciated, ofcourse, that the values of temperature, flow rate, and degree ofoxygenation will be quite interdependent in that particular optimumvalues might be selected for individual patients and/or for differentprocedures.

[0036] The methods of the present invention will-find their greatest usein open and thoracoscopic surgical procedures where the aorta is exposedand surgically opened to permit performance of the desired procedure. Insuch cases, the heart will be arrested and the perfusion of theoxygenated medium will be relied on to achieve adequate oxygenation ofthe brain tissue and to avoid deleterious ischemia. Generally, the flowrates and temperatures set forth above will be sufficient to bothachieve adequate perfusion and avoid ischemia. After the open procedureis completed, and the aorta is surgically closed, heart function may bereestablished. In order to avoid the release of emboli from the aortainto the cerebral vasculature, occlusion of carotid artery(ies) will bemaintained for a minimum amount of time after heart function has beenreestablished, typically for at least about 2 minutes, preferably for atleast about 5 minutes, in order to permit atheromatous debris and air tobe cleared from the aorta and away from the brain.

[0037] Occlusion of the selected arteries with the expansible occludermay be achieved in a variety of ways. Usually, in open surgicalprocedures, the outside of the target artery(ies) will be surgicallyexposed, permitting surgical incisions through the arterial wall(s). Theexpansible occluder may then be introduced through the incision,expanded, and perfusion of oxygenated medium established through theoccluder. Alternatively, the expandable occluders may be introducedpercutaneously through the patient's neck and to the selectedartery(ies) using conventional access techniques, such as the Seldingertechnique. The expansible occluders will typically but not necessarilyinclude catheters, cannulas, or other devices that permit the perfusionof the oxygenated medium through the expansible member and into thecarotid artery for perfusion of the cerebral vasculature. It will alsobe possible to utilize separate devices for occlusion and for theperfusion of oxygenated medium. Fore example, it would be possible toemploy an external clamp on the target artery and to utilize a separateneedle or other cannula for infusion the oxygenated medium upstream ofthe clamp. The use of clamps, however, is generally not preferred sincethey can cause the release of significant amounts of atheromatous debriswhen released. It would also be possible to employ separate occluder(s)and infusion needles/cannulas, where the points of occlusion andinfusion of oxygenated medium could be close together or spaced-apart.Also, as mentioned above, it will be possible to employ devices withmore than one occlusion balloons and/or more than one infusion lumens inorder to occlude and/or infuse oxygenated medium to different points inthe vasculature from a single incision site.

[0038] As an alternative to access at points in the arterial vasculatureabove the aortic arch, the occlusion and perfusion devices may beintroduced intravascularly through sites remote from the aortic arch.Most commonly, intravascular catheters may be introduced by conventionaltechniques through the femoral arteries and advanced to the targetcerebral arteries using conventional techniques. Such access routes,will necessarily involve passing the catheters through the aortic architself. Thus, in many instances, it will be undesirable to use suchintravascular techniques since they will lie within the regions wherethe procedure is being performed. Intravascular access could also beachieved in a retrograde manner through the axillary and brachialarteries as discussed above.

[0039] While it will be possible to perfuse a cold, oxygenated mediumwithout collecting and recycling the medium, it will usually bedesirable to establish a continuous extracorporeal flow circuit forfiltering, oxygenating, and returning patient blood or other oxygenatedmedium to the patient. The oxygenated medium perfused into the arterialcerebral vasculature will generally flow through the anterior andposterior regions of the brain and into the venous system of the brain.From the venous system, the oxygenated medium will flow outwardly fromthe brain, primarily from the jugular veins. Thus, it will be convenientto collect the oxygenated medium from the brain from at least one of theright and left internal jugular veins, preferably from both internaljugular veins, or from the superior vena cava into which the jugularveins drain. This blood can then be returned to the extracorporeal bloodpump, oxygenated, and cooled before return to the patient's arterialcerebral vasculature. Additionally, a very small portion of the blood orother oxygenated medium perfused into the brain through the cerebralarteries may leak back into the aortic arch through the left vertebralartery if the left subclavian artery is not occluded. This leakage,typically in an amount from 5 ml/minute to 25 ml/minute, can besuctioned or otherwise collected by the surgeon and returned to theextracorporeal circulation system.

[0040] The brain and cerebral vasculature are at greatest risk fromembolization and ischemia during the performance of aortic proceduresthat require arresting of the heart. Other portions and tissues withinthe body, however, are also at significant risk and in some cases it maybe desirable to establish a perfusion of oxygenated medium through thenoncerebral vasculature, in particular the vasculature in the lowerportion of the patient's body. For example, oxygenated blood or othermedium can be introduced into the aorta below the aortic arch, where theaortic arch is isolated using an expansible occluder or otherconventional occlusion device. The oxygenated medium will thus flow tothe lower portion of the patient's body where it will collect in thevenous system and be returned towards the patient's heart through theinferior vena cava. By occluding the inferior vena cava, again typicallyusing an expansible occluder, the blood or other oxygenated medium maybe collected and returned to an extracorporeal oxygenation, pumping, andoptional cooling circuit.

[0041] The present invention still further provides kits including oneor more expansible occluders adapted to occlude selected artery(ies) asdescribed above. Such kits will further include instructions for useaccording to any of the methods set forth above. Additionally, the kitmay comprise a package for holding all or a portion of the kitcomponents, typically in a sterile condition. Typical packages includetrays, pouches, boxes, tubes, and the like. Preferably, the cannulaswill each have an occlusion balloon sized to occlude the respectiveblood vessel lumen into which they are placed. Other optional kitcomponents include oxygenated medium, drugs to be delivered via theflowing blood or other oxygenated medium, catheters for connecting thecannulas to an extracorporeal recirculation/oxygenation cooling system,cassettes for use with such extracorporeal recirculation systems,cooling elements, thermometers, pressure transducers, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1 is a schematic illustration of a patient's headillustrating arterial and venous access sites suitable for use in themethods of the present invention.

[0043]FIGS. 2A and 2B illustrate the use of a pair of access cannulasfor perfusing oxygenated medium through the cerebral vasculature of apatient according to the methods of the present invention.

[0044]FIG. 3 illustrates a preferred system constructed in accordancewith the principles of the present invention.

[0045]FIG. 4 illustrates an exemplary kit constructed in accordance withthe principles of the present invention.

[0046]FIG. 5 illustrates the great vessels that exit and enter the heartand which are relevant to the occlusion and circulation patterns of thepresent invention.

[0047] FIGS. 6A-6E illustrate the use of differing arrangements ofexpansible occluders for occluding and directing the flow of oxygenatedmedium to the cerebral arteries according to the methods of the presentinvention.

[0048]FIG. 7 illustrates the occlusion pattern of FIG. 6, with furtherocclusion of the internal jugular veins to collect oxygenated mediumflowing from the venous structure of the brain.

[0049]FIG. 8 illustrates an alternate occlusion pattern for collectingoxygenated medium from the brain, where the superior vena cava isoccluded and all medium flowing into the superior vena cava collected.

[0050]FIG. 9 illustrates an occlusion pattern according to the presentinvention where the lower vasculature of the patient is occluded andperfused with oxygenated medium.

[0051]FIG. 10 is a schematic illustration of a patient undergoing anaortic procedure with an oxygenated medium being supplied according tothe scheme set forth in FIGS. 8 and 9.

[0052]FIG. 11 illustrates a kit constructed in accordance with theprinciples of the present invention.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0053] The present invention provides methods, systems, and kits forperfusing the cerebral vasculature of a patient with an oxygenatedmedium. For the purposes of the present invention, the cerebralvasculature includes all arteries and veins leading into or from thepatient's head, particularly including the common carotid arteries, theexternal and internal carotid arteries, and all smaller arteries whichbranch from the main arteries leading into the head. In some cases,particularly in open surgical procedures, access may be established inthe aortic arch and innominate (brachycephalic trunk) artery as well.Cerebral veins include the external and internal jugular veins, thesuperior vena cava, and the smaller veins which feed into the primaryveins draining the cerebral vasculature. Preferred access points shouldbe at locations in the vasculature which permit relatively directpercutaneous introduction of a needle, cannula, or other access conduitthrough which the flow of oxygenated medium will be established.Exemplary access sites are in those regions of the internal jugular veinIJV and common carotid artery CCA which are readily located and accessedthrough a patient's neck, as illustrated in FIG. 1.

[0054] Usually, only a single arterial and a single venous site need beaccessed. Blood or other oxygenated medium perfused at a flow rate of atleast 0.2 l/min (preferably at least 0.5 l/min) will usually besufficient to go up from the arterial access site, e.g., through eitherthe right or left common carotid artery, perfuse the ipsilateralhemisphere, and to cross over and perfuse the contralateral hemisphereof the brain. Suitable perfusion pressures are in the range from 250mmHg, preferably from 30 mmHg to 160 mmHg. The ipsilateral hemispherewill thus be perfused in an antegrade direction while the contralateralhemisphere and territories supplied by the posterior circulation will beperfused in a retrograde direction. The blood will then flow into thecerebral venous vasculature from where it may be collected at one or twovenous access sites. In this way, the entire brain can be perfused withoxygenated and optionally cooled blood or other oxygenated medium.

[0055] As illustrated in FIGS. 2A and 2B, access will usually beestablished using cannulas 10 and 20, each having inflatable isolationballoons 12 and 22 near their distal ends, respectively. In theillustrated embodiment, the cannulas 10 and 20 are needles havingsharpened distal tips such that the needles may be penetrated throughthe patient's skin S without the need to employ separate stylets,needles, or other access means. The treating personnel are thus able tolocate the appropriate access points on the patient's neck or otherlocation and directly introduce the cannulas 10 and 20 so that theirdistal tips lie within the lumens of the artery A and vein V,respectively. Alternatively, the treating professional may access theartery and/or vein through a small incision or puncture allowingintroduction of a blunt cannula or other access tube.

[0056] Once the cannulas 10 and 20 have been placed, as illustrated inFIG. 2A, the balloons 12 and 22 will be inflated, as illustrated in FIG.2B. The balloons and 12 and 22 partition the cerebral vasculature sothat oxygenated medium introduced through the arterial cannula 10 willtravel upwardly into the cerebral vasculature and will be inhibited fromflowing downwardly to the arterial system below the head. Similarly, theballoon 22 on the venous cannula 20 will prevent the outflow of blood orother oxygenated medium from the cerebral vasculature from flowingdownwardly from the head, allowing efficient collection of the outflowby the cannula 20.

[0057] In the simplest cases, the methods of the present invention mayrely on providing relatively large volumes of oxygenated medium, such asa pre-oxygenated carrier, such as a perfluorocarbon, or pre-oxygenatedheterologous blood, and flowing the oxygenated medium through thearterial cannula 10, through the cerebral vasculature, and out thevenous cannula 20 in a once-through manner. The oxygenated mediumpassing out of the venous cannula will not be recirculated.

[0058] More typically, however, the methods of the present inventionwill rely on circulating the oxygenated medium from the venous cannula20 back to the arterial cannula 10. To circulate the oxygenated medium,it will usually be necessary to oxygenate the medium externally of thepatient, further usually being desirable to also cool the medium tolower the temperature of the brain. Such external oxygenation andoptional cooling may be provided by a system 50 as illustrated in FIG.3. The system 50 includes a pump 52, typically a peristaltic pump, acooler 54, a temperature gauge 56, and a port 58 for infusing cerebralprotective agents and/or other drugs or biologically active substances.Such systems are analogous to the cardiopulmonary bypass systems used inheart and vascular surgery. Suitable portable bypass pumps andoxygenators are described in U.S. Pat. No. 4,540,399; U.S. Pat. No.5,011,469; and U.S. Pat. No. 5,149,321, the full disclosures of whichare incorporated herein by reference. The systems described in thesepatents, however, are generally intended for maintaining artificialcirculation through all or a substantial portion of the patient's entirevasculature. The systems of the present invention will generally bemodified to provide blood or other oxygenated medium at lower flow rateswithin the ranges set forth above.

[0059] Optional features of the cannulas 10 and 20 illustrated in FIG. 3include separate inflation conduits 13 and 23 for inflating balloons 12and 22, respectively. The inflation conduits may be connected tosyringes or other conventional devices for selectively inflating theballoons after the cannulas 10 and 12 have been properly positionedwithin the target blood vessels. Additionally, ports 14 and 24 may beprovided near the sharpened distal tips of the cannulas 10 and 12,respectively. Alternatively, the distal tips of the cannulas couldsimply have a chamfered, sharpened distal tip where flow passes directlyout the tip. As a further alternative, the cannulas 10 and 12 could beprovided with simple stylets which permit self-introduction. Afterintroduction, the stylets could be quickly removed to provide an openflow lumen at the tip.

[0060] Referring now to FIG. 4, kits according to the present inventionwill comprise at least cannulas 10 and 20 and instructions for use (IFU)75. The cannulas 10 and 20 will be suitable for connection to anextracorporeal flow system 50, or for connection to a reservoir ofoxygenated medium, depending on the intended use. The instructions foruse 75 will set forth any of the methods described above. Usually, thecatheters 10 and 20 and instructions for use 75 will be packagedtogether in a suitable package 80, such as a pouch, tray, box, tube, orthe like. Optionally, the instructions for use may be printed in wholeor in part on a portion of the packaging 80. Usually, at least thecatheters 10 and 20 will be sterilely maintained within the package 80.Other optional kit components which could be placed within the package80 include oxygenated medium, cerebral protective agents and/or otherdrugs, additional catheters for connecting the cannulas to system 50 orother extracorporeal apparatus, replaceable cassettes for system 50which permit replacement of all system components which directly contactthe blood, and the like.

[0061] Referring now to FIG. 5, systemic circulation relevant to themethods of the present invention will be briefly described. Oxygenatedblood from the heart normally flows upwardly through the aortic arch andthen downward to the lower portions of the body through the thoracicaorta. Three major arteries extend upwardly from the top of the aorticarch. The brachiocephalic artery branches into the right carotid arteryand the right subclavian artery. In contrast, the left carotid arteryand left subclavian artery extend directly from the aortic arch and donot have a common portion. Together, the right common carotid artery andleft common carotid artery provide oxygenated blood to most parts of thehead and neck. They ascend through the anterior neck just lateral to thetrachea and are covered by relatively thin muscles which permits directpercutaneous access via cut-down or needle introduction (the Seldingertechnique) in certain embodiments of the present invention. In additionto the carotid arteries, oxygenated blood is provided to the brainthrough the vertebral arteries, although to a significantly lesserextent.

[0062] As will be described in more detail below, the methods of thepresent invention will rely on internally occluding blood flow from theaortic arch to at least one common carotid artery, and preferably bothcommon carotid arteries. Occlusion of blood flow from the aortic arch tothe right common carotid artery may be effected by occluding the bloodflow lumen in the brachiocephalic artery and/or the right common carotidartery itself. Occlusion of the left common carotid artery will takeplace in a lumen of the left common carotid artery itself, andoptionally either or both of the right and left vertebral arteries mayalso be directly or indirectly occluded. Blood or other oxygenatedmedium will be provided to the cerebral arterial vasculature through atleast some of the occluded arteries by perfusing a medium to theartery(ies) at a point distal to the occlusion. As the carotid arteriessupply most of the blood flow to the brain, it will not be necessary toocclude the vertebral arteries and/or provide oxygenated blood to thebrain through the vertebral arteries. While some leakage of blood backto the aorta may occur through the vertebral arteries, such leakage isminor and can be removed from the aortic arch using conventional suctiondevices.

[0063] By occluding blood flow to the right common carotid artery usingan occluder present in the brachiocephalic artery, blood supplied distalto the occluder will flow to both the right common carotid artery andthe right vertebral artery. Thus, it will usually be preferred toocclude flow to the right common carotid artery at a point within thebrachiocephalic artery. It will be appreciated, of course, that byproviding the perfusion of oxygenated medium distally of thebrachiocephalic artery, blood will flow not only to the right commoncarotid artery and right vertebral artery, but also toward the armthrough the right subclavian artery. Thus, in order to inhibit the flowof oxygenated medium to the arm and redirect such flow to the cerebralarteries, it will in some cases be desirable to provide a tourniquet onthe right arm. Alternatively, an occlusion balloon could be locatedwithin the lumen of the right subclavian artery to point downstream fromthe right vertebral artery branch. Optionally, a catheter having a pairof balloons could be used, where one balloon occludes within thebrachiocephalic artery and a second, more distal balloon occludes withinthe right subclavian artery.

[0064] Occlusion of the left vertebral artery may be effected in eitherthe left subclavian artery, usually at a point near the branch with theaortic arch, or within the left vertebral artery itself. Occlusionwithin the left subclavian artery is generally preferred since it willinhibit passage of atheromatous material into the entire arterialstructure branching from the left subclavian artery. Moreover, byperfusing oxygenated medium beyond the point of occlusion, that mediumwill flow into the left vertebral artery to supply the left cerebralarterial vasculature. Loss of blood to the patient's arm can beinhibited by applying a tourniquet to the left arm.

[0065] The venous system of the brain drains primarily through the rightinternal jugular vein and the left-internal jugular vein. These veins,in turn, drain into the superior vena cave where the oxygen-depletedblood is returned to the heart. Blood supplied to the lower body throughthe thoracic aorta returns to the heart through the inferior vena cava.

[0066] Referring now to FIG. 6A, a first exemplary method for accessingan aorta according to the present invention comprises internallyoccluding the right common carotid artery at a point above the aorticarch. Typically, the occlusion may be achieved using expansibleoccluders, such as balloon-tipped cannula 10 that is placed in a lumenof the right common carotid artery. The balloon may be any conventionaltype of balloon commonly used for blood lumen occlusion, e.g., beingelastomeric balloons having a generally spherical geometry. The balloonswill be expandable to a size in the range from 3 mm to 20 mm, typicallyat a relatively low inflation pressure on the order of 2 atmospheres to5 atmospheres. The expansible occluders may be introduced surgically,percutaneously, or intravascularly, as discussed above.

[0067] Most commonly, the surgeon accessing the aorta will extend theincision so that the exterior surfaces of each carotid artery areexposed. A small surgical incision can then be made and the exposed wallof the artery and the occlusion balloon introduced in a conventionalmanner. Alternatively, the balloon may be percutaneously introduced viaa cut-down procedure or using a needle, guidewire, and appropriateinsertion sheath using conventional techniques, such as the Seldingertechnique. In all cases, after occlusion is achieved, the oxygenatedmedium may be introduced through the cannula, typically within the flowrate and temperature ranges set forth above. It will also be desirableto monitor and control the pressure of the oxygenated medium beingintroduced, typically within a range of about 10 mmHg to 200 mmHg,preferably from 30 mmHg to 90 mmHg. The blood may be introduced in acontinuous, non-pulsatile flow.

[0068] By occluding only the right common carotid artery, as shown inFIG. 6A, the oxygenated medium will be provided only to the rightarterial cerebral vasculature. Moreover, as none of the right vertebralartery, left common carotid artery, nor left vertebral artery areoccluded, those arteries are placed at risk at receiving atheromatousmaterial, particularly when heart function is reestablished. Thus, itwill frequently be desirable to occlude at least the right commoncarotid artery with the balloon-tipped cannula 10 and the left commoncarotid artery with a second balloon-tipped cannula 12, as shown in FIG.6B. Oxygenated medium may then be perfused through either or both of thecannulas 10 and 12, preferably through both. Further optionally,cannulas 10, 12, 14, and 16 may be disposed within the lumens of theright common carotid artery, left common carotid artery, right vertebralartery, and left vertebral artery, respectively, as shown in FIG. 6C.Such an arrangement is advantageous because it both reduces the risk ofentry of atheromatous material into the cerebral vasculature andprovides for multiple access points for introducing oxygenated medium tothe cerebral vasculature.

[0069] The arrangement of cannulas shown in FIG. 6C is not optimal forat least two reasons. First, it requires the use of four separatecannulas. Second, atheromatous material from the aortic arch can enterboth the right subclavian artery and the left subclavian artery sincethe entry points to these arteries are not occluded. Thus, an improvedarrangement of multiple cannulas is shown in FIG. 6D. There, a firstballoon-tipped cannula 100 is placed into the brachiocephalic artery andpositioned to perfuse oxygenated medium to the cerebral vasculaturethrough both the right common carotid artery and right vertebral artery.Loss of oxygenated medium to the right arm may be inhibited by placing atourniquet 102 on the arm. A second balloon-tipped catheter 12 may beplaced in the left common carotid artery, generally as described above.A third balloon-tipped catheter 104 is placed in the left subclavianartery relatively near the branch point from the aortic arch. Placementnear the aortic arch branch will enhance the isolation of the arterialsystem branching from the left subclavian artery. Moreover, oxygenatedmedium perfused distally of the balloon-tipped cannula 104 will flowupwardly through the left vertebral artery into the left cerebralarterial vasculature. Loss of such oxygenated medium may be inhibited byplacing a second tourniquet 106 on the patient's left arm.

[0070] As illustrated thus far, the balloon-tipped cannulas haveincluded only single balloons and have been introduced through thevascular wall at a point immediately adjacent to the point of occlusion.As discussed above, however, the cannulas need not be introducedadjacent to the point of occlusion nor do they need to be simple,single-balloon catheters. An alternative balloon-tipped catheterarrangement employing a cannula 120 having a pair of a balloons 122 and124 as illustrated in FIG. 6E. The cannula 120 may be introduced in aretrograde fashion through the right subclavian artery, optionally froman artery of the arm, such as the axillary artery or the brachialartery. The cannula 120 is advanced so that the distal-most balloon 124is disposed within the lumen of the brachiocephalic artery. By inflatingthe balloon 124, blood flow from the aortic arch to the vasculatureabove the brachiocephalic artery is occluded. By inflating balloon 122,blood flow through the right subclavian artery at points distal to thebranch of the right vertebral artery is also occluded. Perfusion ports123 are provided on the cannula 120 between the distal-most balloon 124and second balloon 122, and oxygenated medium may be introduced throughthe perfusion ports to flow to both the right vertebral artery and theright common carotid artery. Moreover, flow out the right subclavianartery beyond balloon 122 is also occluded, helping to directsubstantially all flow of oxygenated medium to the cerebral vasculature.Usually, the second balloon-tipped catheter 12 will be disposed withinthe left common carotid artery and further optionally (although notshown) one or more balloon-tipped catheters may be used to occlude flowto the left vertebral artery, as shown in either FIG. 6C or 6D.

[0071] When the oxygenated medium is autologous patient blood, it willbe necessary to collect at least a portion of the oxygen-depleted bloodafter it has passed through the cerebral vasculature and to return thatblood to the patient after filtering, reoxygenation, and optionalcooling. The blood may be collected in the venous vasculature whichdrains the brain, typically by placing a pair of expansible occluders 20and 22 into the right internal jugular vein and left internal jugularvein, respectively, as illustrated in FIG. 7. The expansible occluder 20and 22 may be constructed similarly to the expansible occluders 10 and12, but will include distal tips 24 and 26, respectively, having aplurality of ports adapted to collect the oxygen depleted blood as itflows toward the heart. As an alternative to blocking the internaljugular veins with a pair of expansible occluders, the superior venacava may be blocked with a single expansible occluder 30, as illustratedin FIG. 8. In both cases, the blood or other oxygen depleted mediumcollected in the venous side of the vasculature will be returned to anextracorporeal system for reoxygenation, pumping, and optional cooling,as will be described in more detail in connection with FIG. 10 below:The expansible occluders 20, 22, and 30, will be sized and adapted to besurgically or percutaneously introduced to the associated vein.

[0072] In addition to isolation and perfusion of the cerebralvasculature by any of the techniques described above, the presentinvention also provides for optional perfusion of non-cerebral portionsof the patient vasculature, particularly the lower body vasculature asillustrated in FIG. 9. Conveniently, the lower body vasculature may beperfused by introducing blood or other oxygenated medium into thedescending aorta using an expansible occluder 40, typically a ballooncatheter, optionally a balloon catheter adapted for introduction throughthe femoral artery in a conventional manner. The expansible occluder 40will include flow ports, which are disposed below the balloon when acatheter is placed within the thoracic aorta. This way, the oxygenatedmedium will flow downwardly from the balloon into the lower arterialvasculature. After perfusing through tissue in the lower body, theoxygen depleted blood or other medium will flow into the venous systemand ultimately upwardly through the inferior vena cava. By placing anexpansible occluder 50 within the lumen of the inferior vena cava may beoccluded and the return blood flow collected. The collected blood maythen be circulated through an extracorporeal recirculation system, asdescribed in more detail in connection with FIG. 10.

[0073] Referring now to FIG. 10, a patient P is undergoing an opensurgical procedure through a sternotomy S that exposes the aortic archAA and the superior vena cava SVC. Expansible occluders 10 and 12 arethen placed into the right and left common carotid arteries,respectively, and connected brachiocephalic to an extracorporealoxygenator and pump 70. Expansible occluder 30 (as illustrated in FIG.8) is introduced to the superior vena cava SVC and also connected to theexternal oxygenator and pump 70. Blood is introduced to the commoncarotid arteries through the expansible occluders 10 and 12 and returnto the external oxygenator and pump through the expansible occluder 30.A reservoir of blood is maintained within the external oxygenator andpump 70 so that sufficient blood will remain in circulation even as acertain amount of blood is lost since it flows outwardly to points otherthan the superior vena cava.

[0074] Preferably, perfusion and oxygenation of the lower portion of thepatient P is accomplished using expansible occluders 40 and 50 which areintroduced intravascularly according to conventional techniques, such asthe Seldinger technique. In this way, the cerebral vasculature and lowerbody vasculature may be continuously perfused with oxygenated bloodwhile blood is kept out of the aorta and the aorta may be opened forperforming a desired procedure.

[0075] For open surgical procedures as illustrated in FIG. 10, thepatient's heart will be arrested using conventional techniques.Typically, the heart will be catheterized and cooled, and supplied withcardioplegia, according to known techniques. The aorta, typically at theaortic arch, may then be opened and a desired procedure performed. Afterthe procedure is complete, cardioplegia will be stopped—the heart willbe warmed, and heart function reestablished.

[0076] A particular advantage of the present invention is that thecerebral vasculature may continue to be isolated during the periodimmediately following cessation of bypass and reestablishment of heartfunction. It will be appreciated that any procedure performed in andaround the aorta may leave significant debris in the aortic lumenpresenting a substantial risk of embolization to the patient. Byreestablishing heart function and blood flow through the aorta whilemaintaining isolation of the cerebral vasculature, the potentiallyembolic material may be cleared from the aorta and removed to lesssensitive portions of the vasculature. Blood flow to the cerebralvasculature can then be reestablished, typically from 2 minutes to 5minutes following the restarting of the heart.

[0077] Referring now to FIG. 11, kits according to the present inventionwill comprise at least one expansible occluder 10, usually comprising atleast two expansible cannulas 10 and 12, as illustrated, instructionsfor use (IFU) 75. The expansible occluders 10 and 12 will be suitablefor connection to an extracorporeal flow system 70 (FIG. 10), or forconnection to a reservoir of oxygenated medium, depending on theintended use. The instructions for use 75 will set forth any of themethods described above. Usually, the expansible occluders 10 and 12 andinstructions for use 75 will be packaged together in a suitable package80, such as a pouch, tray, box, tube, or the like. Optionally, theinstructions for use may be printed in whole or in part on a portion ofthe packaging 80. Usually, at least the expansible occluders 10 and 12will be sterilely maintained within the package 80. Other optional kitcomponents which could be placed within the package 80 includeoxygenated medium, cerebral protective agents and/or other drugs,additional catheters for connecting the cannulas to system 70 or otherextracorporeal apparatus, replaceable cassettes for system 70 whichpermit replacement of all system components which directly contact theblood, and the like.

[0078] While the above is a complete description of the preferredembodiments of the invention, various alternatives, modifications, andequivalents may be used. Therefore, the above description should not betaken as limiting the scope of the invention which is defined by theappended claims.

What is claimed is:
 1. A method for cerebral cooling, comprising thesteps of: inserting a first catheter into a right common carotid arteryand expanding an occlusion member disposed about the first catheter;inserting a second catheter into a left common carotid artery andexpanding an occlusion member disposed about the second catheter;inserting a third catheter into an inferior vena cava and expanding anocclusion member disposed about the third catheter; flowing oxygenatedmedium from the first catheter into the right common carotid artery;flowing oxygenated medium from the second catheter into the left commoncarotid artery; and withdrawing medium from the inferior vena cava. 2.The method of claim 1, further comprising the step of stopping bloodflow within the aorta.
 3. The method of claim 1, further comprising thestep of performing a diagnostic or interventional procedure on theaorta.
 4. The method of claim 1, further comprising the step ofperforming an open surgical interventional procedure on the aorta. 5.The method of claim 1, further comprising the step of performing repairof an aortic aneurysm, repair of an aortic dissection, reconstruction ofthe aorta, or endarterectomy.
 6. The method of claim 1, furthercomprising the step of inserting a fourth catheter into a descendingaorta and expanding an occlusion member disposed about the fourthcatheter.